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SIG Sauer

SIG MPX Copperhead

Ultra-compact short-stroke gas piston PCC

Key Highlights

  • 3.5-inch barrel
  • Gas piston operated
  • Monolithic upper

Specifications

Price
$1,835
Weight
4 lb 8 oz
Calibers
9mm
Rail Type
mlok

Capability Profile

0-10 Scale Across 8 Axes

Compatibility Tags

family: pccmag-type: mpxinterface: picatinny-tophandguard: mlokbarrel: ultra-compactstock-interface: picatinny-1913

Overview

The SIG MPX Copperhead is one of the most compact factory PCC-format pistols available, measuring about 14.5 inches overall. The 3.5-inch barrel sacrifices velocity for maximum compactness, creating a package that's barely larger than some full-size handguns but offers rifle-like control and 30-round capacity.

Unlike most PCCs, the MPX uses a short-stroke gas piston system rather than blowback. This reduces felt recoil and bolt carrier mass compared to blowback designs, making the platform smoother shooting. The system also makes the MPX less sensitive to ammunition power levels and suppressor backpressure than direct blowback competitors.

The Copperhead features SIG's monolithic upper receiver with integrated handguard, creating a rigid and streamlined package. Suppressor-readiness depends on the exact Copperhead SKU and muzzle setup, so buyers should verify the barrel/muzzle configuration before planning a can around it. For users who need maximum compactness without sacrificing rifle-like capability, the Copperhead delivers a very small MPX package.

Key Features

  • 3.5-inch barrel for ultra-compact size
  • Short-stroke gas piston operation
  • Monolithic upper receiver
  • 14.5 inches overall length on the legacy official reference SKU
  • AR-style controls
  • 30-round magazine capacity
  • Timney trigger ready

Pros

  • +Most compact factory PCC available
  • +Gas piston reduces recoil vs. blowback
  • +Folds to extremely small package
  • +30-round capacity maintained
  • +AR-familiar controls
  • +Quality SIG construction

Cons

  • Significant velocity loss from short barrel
  • Premium price point
  • Proprietary MPX magazines
  • Limited rail space on short handguard
  • Loud with short barrel

Detailed Specifications

caliber
9mm
Barrel Length
3.5 inches
Overall Length
14.5 inches
weight
4.5 lbs
Gas System
Short-stroke gas piston
barrel
Carbon steel, nitride finish
handguard
Monolithic with M-LOK
trigger
Single-stage, Timney ready
sku
PMPX-3B-CH
msrp
$1,835

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